The present invention relates to a solar-energy collector.
A solar-energy collector of this kind is known from U.S. Pat. No. 4,569,330. A tray-like part of the casing and a cover plate attached to the upper edges of this tray-like part form a box-shaped casing of constant volume enclosing a dry gas. The presence of dry gas prevents condensation forming inside the solar-energy collector. Neither can impurities or harmful substances originating from the insulating material of the solar-energy collector penetrate into the interior thereof. The casing must therefore consist of a material which is proof diffusion, such as sheet steel and glass for example, which is acceptable from the aspect of cost. The dry gas, which may suitably be nitrogen gas, also excludes the risk of corrosion within the solar-energy collector, since the gas guards against oxidation and against the aging of any sealing material or the like which may be present.
The enclosed gas must not be subjected to wide variations in pressure as a result of variations in temperature, in view of the subsequent risk of leakage or of other damage, such as fatigue fracture and the formation of cracks.
This has been avoided in the known solar-energy collector construction, by arranging for the cavity within the collector to communicate with a container located externally of the solar-energy collector and made of a diffusion-proof, light pliable material, such as a bag made of plastic/aluminium-foil laminate for example. The disadvantage with this solution resides in the manual assembly work required, which tends to increase the overall costs, and in that the container, when it is to be placed in a compartment provided therefor in the insulation on the rear side of the casing, takes up a relatively large part of the space intended for the insulation. The volumetric capacity required of the container in order to prevent changes in pressure during filling and subsequent emptying operations is quite considerable, and corresponds to at least 50% of the volume of the box-shaped casing.